The actresses said the trust has made 'vital contributions' to the Northern Ireland peace process and the transition to democracy in South Africa. They wrote that charities such as the trust frequently work in 'complex and difficult environments' to promote peace, justice and equality.

Their co-signatories included Sir Christopher Bland, a former chairman of the BBC, and former Labour leader Lord Kinnock.

'At times its work has been risky or controversial, but in our experience it has always acted with the greatest integrity,' they said in a letter to The Times.

The trust, along with the Roddick Foundation, was investigated by the Charity Commission over support for Cage.

The trust reluctantly agreed to stop bankrolling Cage after Charity Commission officials threatened it with a statutory inquiry.

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Asim Qureshi, its research director, described one of the world's most wanted terrorists as a 'beautiful young man' and 'extremely gentle'

Cage caused outrage over its attempts to justify the killings meted out by Kuwaiti-born Briton Emwazi, because he had claimed to have been harassed by MI5.

The campaign group gave an extraordinary press briefing about Emwazi – carried live at length on the BBC and Sky – after he was identified as the man behind the mask of Jihadi John.

Asim Qureshi, its research director, described one of the world's most wanted terrorists as a 'beautiful young man' and 'extremely gentle'.

The 32-year-old blamed British security services for the radicalisation of Emwazi.

The group has been propped up largely by the Joseph Rowntree Charitable Trust since 2007, with grants making a combined total of £305,000.